Protein extraction from formalin-fixed, paraffin-embedded tissue sections: quality evaluation by mass spectrometry

Area of Science:

• Biochemistry
• Molecular Biology
• Histopathology

Background:

• Archival formalin-fixed, paraffin-embedded (FFPE) tissues are valuable resources for retrospective studies.
• Efficient protein extraction from FFPE tissues is crucial for proteomic analysis but remains challenging.
• The antigen retrieval (AR) technique, commonly used in immunohistochemistry, shows potential for protein extraction.

Purpose of the Study:

• To establish and optimize a heat-induced protein extraction protocol for FFPE tissue sections.
• To compare the efficiency and quality of protein extraction from FFPE tissues versus fresh tissues.
• To validate the extracted proteins using gel electrophoresis and mass spectrometry.

Main Methods:

• Developed a heat-induced protein extraction protocol based on the antigen retrieval (AR) technique.
• Optimized the protocol using FFPE mouse tissues.
• Applied the optimal protocol to human renal carcinoma FFPE tissues and compared it with conventional radioimmunoprecipitation assay (RIPA) buffer extraction from fresh tissue.

Main Results:

• A satisfactory protein extraction protocol using heat-induced AR in Tris-HCl with 2% SDS was established.
• Gel electrophoresis and mass spectrometry analysis showed significant overlap in identified proteins between FFPE and fresh tissues.
• Heating treatment was essential for efficient protein extraction from FFPE sections.

Conclusions:

• Heat-induced antigen retrieval provides an effective method for protein extraction from archival FFPE tissue sections.
• Proteins extracted from FFPE tissues using this method are comparable to those extracted from fresh tissues.
• This protocol enhances the utility of FFPE samples for proteomic research.